Background Ischemic heart disease and heart failure often lead to sexual difficulties in men, but little is known about the sexual difficulties in women and patients with other heart diagnoses or the level of information patients receive about the risk of sexual difficulties. Aim To investigate perceived sexual difficulties and associated factors in a mixed population of men and women newly diagnosed with heart disease and provide insight into sexual counseling and information given by health care professionals. Methods This article reports on a cross-sectional, questionnaire study sent to a randomly selected sample of men and women newly diagnosed with heart failure, ischemic heart disease, atrial fibrillation, or heart valve surgery. Eligible patients were identified by diagnosis using the Danish National Patient Register, which contains all diagnoses. Outcomes Sexual difficulties were self-reported using single-item questions, and factors associated with sexual difficulties were collected from the survey and national registers. Results The study population consisted of 1,549 men and 807 women (35–98 years old) with heart failure (n = 243), ischemic heart disease (n = 1,036), heart valve surgery (n = 375), and atrial fibrillation (n = 702). Sexual difficulties were reported by 55% of men and 29% of women. In a multiple regression analysis, difficulties in men were associated with being older (≥75 years old; odds ratio [OR] = 1.97, 95% CI = 1.13–3.43), having heart failure (OR = 2.07, 95% CI = 1.16–3.71), diabetes (OR = 1.80, 95% CI = 1.15–2.82), hypertension (OR = 1.43, 95% CI = 1.06–1.93), receiving β-blockers (OR = 1.37, 95% CI = 1.02–1.86), or having anxiety (OR = 2.25, 95% CI = 1.34–3.80) or depression (OR = 2.74, 95% CI = 1.38–5.43). In women, difficulties were significantly associated with anxiety (OR = 3.00, 95% CI = 1.51–5.95). A total of 48.6% of men and 58.8% of women did not feel informed about sexuality, and 18.1% of men and 10.3% of women were offered sexual counseling. Clinical Implications Heart disease increases the risk of sexual difficulties and there is a need for improved information and counseling about sex and relationships for patients. Strengths and Limitations This large nationwide survey of men and women combined a survey with administrative data from national registries. However, this study used non-validated single-item questions to assess sexual difficulties without addressing sexual distress. Conclusion More than half the men and one fourth the women across common heart diagnoses had sexual difficulties. No difference was found among diagnoses, except heart failure in men. Despite guidelines recommending sexual counseling, sexual difficulties were not met by sufficient information and counseling. Rundblad L, Zwisler AD, Johansen PP, et al. Perceived Sexual Difficulties and Sexual Counseling in Men and Women Across Heart Diagnoses: A Nationwide Cross-Sectional Study. J Sex Med 2017;14:785–796.